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Abstract

Background

Fear of crime is associated with negative health and wellbeing outcomes, and may mediate
some impacts of the built environment on public health. A range of environmental interventions
have been hypothesized to reduce the fear of crime.

Methods

This review aimed to synthesize the literature on the effectiveness of interventions
in the built environment to reduce the fear of crime. Systematic review methodology,
following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)
guidance, was used. Studies of environmental interventions which reported a fear of
crime outcome and used any prospective evaluation design (randomized controlled trial
(RCT), trial or uncontrolled before-and-after study) were included. Eighteen databases
were searched. The Hamilton tool was used to assess quality. A narrative synthesis
of findings was undertaken.

Results

A total of 47 studies were included, 22 controlled and 25 uncontrolled, with total
sample sizes ranging from n = 52 to approximately n = 23,000. Thirty-six studies were
conducted in the UK, ten studies in the USA and one study in the Netherlands. The
quality of the evidence overall is low. There are some indications that home security
improvements and non-crime-related environmental improvements may be effective for
some fear of crime outcomes. There is little evidence that the following reduce fear
of crime: street lighting improvements, closed-circuit television (CCTV), multi-component
environmental crime prevention programs or regeneration programs.

Conclusions

There is some evidence for the effectiveness of specific environmental interventions
in reducing some indicators of fear of crime, but more attention to the context and
possible confounders is needed in future evaluations of complex social interventions
such as these.

Keywords:

Background

Fear of crime is known to be associated with a number of negative mental and physical
health outcomes [1]. The fear of crime may cause mental health problems directly, and it may also reduce
outdoor physical activity and social interaction [1]. Conversely, mental health problems may increase fear of crime, potentially leading
to a feedback effect which can exacerbate both [2,3]. Crime itself also appears to have negative impacts on health: rates of violent crime
at neighborhood level have been found to be associated with a range of health behaviors
and outcomes [1,4]. This suggests that interventions to reduce crime or the fear of crime may potentially
be a way to improve health and wellbeing outcomes, particularly mental health, at
a community level.

Furthermore, both crime and the fear of crime may be influenced by factors in the
built environment. The impact of built environment factors on crime rates have been
a focus of Crime Prevention Through Environmental Design (CPTED) theory, which emphasizes
factors such as natural surveillance and access control as environmental determinants
of crime [5,6]. Several built environment interventions are known to be effective in reducing crime,
including street lighting [7] and environmental programs for robbery prevention in retail settings [8]. Fear of crime is also associated with environmental factors such as litter, graffiti
and patterns of land use (for example residential versus non-residential) [1]. Combining these pathways, it appears that crime and the fear of crime may mediate
the effects of the physical environment on public health [9].

Thus, interventions involving changes to the physical environment may be a promising
way to address fear of crime, and the broader health and wellbeing impacts of crime.
The built environment has been identified as a key locus of intervention to reduce
health inequalities by addressing ‘upstream’ social determinants of health outcomes
[10]. That is, environmental changes can help to address the macro-level determinants
of health behaviors, not only in disadvantaged areas, but also across the population
as a whole. However, this point has received less attention in the field of crime
prevention [11]. (Indeed, in criminology a focus on physical environmental factors has arguably been
associated with the opposite shift, away from the upstream determinants of crime and
towards individual-level situational determinants.) Therefore, focusing on environmental
interventions also helps to bridge the hitherto largely distinct fields of public
health and crime prevention. The aim of this review was to synthesize the evidence
of the effectiveness of environmental interventions on fear of crime.

Search strategy and inclusion criteria

The following databases were searched: Applied Social Sciences Index and Abstracts
(ASSIA), Cumulative Index to Nursing and Allied Health Literature (CINAHL), Conference
Proceedings Citation Index, Criminal Justice Abstracts, Dissertation Abstracts, EconLit,
Embase, Education Resources Information Center (ERIC), Health Management Information
Consortium (HMIC), Inside Conferences, MEDLINE, National Criminal Justice Reference
Service (NCJRS), PsycINFO, Science Citation Index, Social Policy and Practice, Social
Sciences Citation Index, Sociological Abstracts, and Urban Studies Abstracts. Searches
were conducted between November 2010 and January 2011. All sources were searched from
inception to the most current records, without date or language restrictions. Terms
used in the search included terms for fear of crime, crime, antisocial behaviour,
and factors and interventions in the built environment. The full MEDLINE search strategy
can be found in web-only Additional file 1 (searches for other databases used a modified form of the MEDLINE search strategy).
In addition, we also searched Google and Google Scholar; scanned the reference lists
of included studies; searched websites of various government bodies, research groups
and other relevant organizations; and consulted the review Advisory Group.

Inclusion criteria were as follows: 1. intervention involving a substantial change
to the built environment; 2. study reporting data on any fear of crime-related outcome,
including perceptions or feelings of safety, estimations of one’s own risk, worry
about specific crimes or crime in general, or any other crime-related affective outcome
or crime-related avoidance behaviors; 3. prospective intervention evaluation of any
design, including randomized controlled trials (RCTs), trials and uncontrolled before-and-after
studies (with non-randomized studies required to report outcome data both before and
after the intervention); and 4. study conducted in a country which is a current member
of the Organization for Economic Co-operation and Development (OECD).

An initial sample of 10% of abstracts was screened by two reviewers independently
and differences resolved by discussion. The remainder of the abstracts was screened
by one reviewer alone. At full-text screening stage, 50% of the included studies were
screened by two reviewers independently.

Data extraction and quality assessment

Data were extracted from the studies using a standardized form, which included information
on the context and setting of the study, population, methodology and findings. Data
extraction and quality assessment for all studies were carried out by a single reviewer
and a sample was double-checked in detail by a second reviewer.

Quality assessment for the effectiveness review was carried out using a version of
the Hamilton tool [12], as modified by Thomson et al. [13]. This tool includes six domains: selection bias, study design, confounders, blinding,
data collection, and withdrawals and dropouts. These domains were used to produce
an overall quality rating: A (high quality), B (medium quality) or C (low quality),
using the algorithm set out in web-only Additional file 2.

Additional file 2.Quality assessment for the systematic review of effectiveness.

Data synthesis

Data were synthesized narratively according to intervention type. Studies were not
excluded based on their quality ratings, but more emphasis was placed on higher quality
studies when reporting and interpreting the results. Meta-analysis was not carried
out, owing to the substantive and methodological heterogeneity of the studies. Since
many studies measure several distinct fear of crime outcomes, an indicative quantitative
summary measure was developed. We standardized all measures to a 0 to 100 scale, inverted
where necessary so that substantively positive findings (for example reduced fear
or increased perceived safety) were expressed in the same direction (as a positive
number). We then calculated a median effect size across all relevant outcomes for
each study, expressing relative changes for studies using controlled designs (the
difference of baseline and post-test differences between intervention and comparison
group) and within-group changes for studies using uncontrolled designs (the difference
between pre- and post-intervention). We also extracted data on population subgroups
(age, gender, ethnicity and socioeconomic status) and conducted a separate narrative
synthesis of these data to identify any equity implications.

Results

Flow of literature through the review

Figure 1 shows the flow of literature through the review. Forty-seven studies were included
in the review.

Intervention content and quality assessment

Table 1 shows the quality ratings assigned to the studies, the study designs used and a brief
description of the content of the intervention.

Table 1.Characteristics and quality ratings of the studies in the effectiveness review (n
= 47)

Sample size indicates sample at baseline in intervention and control groups, or total
for non-comparative studies; ‘total’ shown for comparative studies where only total
sample size is reported. Follow-up shows time from completion of intervention to latest
outcome measurement for which data are available, except studies marked ‘a’ which indicates follow-up measured from the start of the intervention. Quality ratings:
A, high quality; B, medium quality; C, low quality. CBA(S), controlled before-and-after
study with same participants before and after; CBA(D+), controlled before-and-after
study with different participants before and after, and with no evidence of change
in population; CBA(D−), controlled before-and-after study with different participants
before and after, and with some evidence of change in population; CCTV, closed-circuit
television; CPTED, Crime Prevention Through Environmental Design; I/C, intervention/control
group; NR, not reported; RCT, randomized controlled trial; UBA(D), uncontrolled (single-group)
before-and-after study with different participants before and after; UBA(S), uncontrolled
(single-group) before-and-after study with same participants before and after.

As shown in Table 1, seven categories of interventions were distinguished: 1. Home security improvements
(some of these interventions also included other components); 2. installation or improvement
of street lighting; 3. installation of closed-circuit television (CCTV) systems; 4.
multi-component interventions for crime prevention (most focused on public areas);
5. housing improvement and relocation; 6. area-based regeneration initiatives (involving
a broad range of components); and 7. small-scale environmental improvements in public
areas. Of these, categories 1 to 4 include interventions whose main aim was to reduce
or prevent crime and/or the fear of crime, while categories 5 to 7 include interventions
which did not have such an aim, but which measured the effect of the intervention
on fear-of-crime-related outcomes.

Study quality overall was generally low: 10 studies were graded as high quality (A),
three as medium quality (B) and 34 as low quality (C). The generally low ratings primarily
reflect two aspects of the evidence base: the large number of uncontrolled studies,
or studies using an inadequately matched control group; and the incomplete reporting
of methods, particularly relating to sampling and recruitment.

The findings are summarized for each intervention category. Within each category the
findings from higher-quality, controlled studies are presented first, followed by
those from uncontrolled studies.

1. Home security improvements

Five studies were identified in this category, all from the UK. The interventions
covered a range of approaches. One study was narrowly focused on providing security
improvements to homes [14], while the other studies combined home security with a range of other security and
non-security improvements. In one study, security improvements were undertaken within
the context of a telecare intervention for older people in sheltered housing [16]. In another study, the security improvements formed part of a broader program of
work, which also included broader improvements to homes as well as to the surrounding
area (including improved lighting, landscaping and alley gating) [17].

Two controlled studies found reductions in fear of crime as a result of home security
improvements (15% [14] and 16% [16]). One uncontrolled study reported similar reductions (18% [17]), while two other uncontrolled studies found no change in fear of crime outcomes
(0.1% across both studies [18,19]).

Overall, the evidence indicates that home security improvements in a range of different
contexts may be promising for reducing fear of crime.

2. Installation or improvement of street lighting

Sixteen studies, four controlled and twelve uncontrolled, investigated the effects
of street lighting improvements on fear of crime. Fifteen studies were conducted in
the UK and one in the Netherlands.

Fourteen studies looked at the effect of improving lighting at an area level on fear
of crime in general. Four of these studies used controlled designs [20,32-34]. Of these, two found that the intervention did not reduce fear (−1.5% for one study
[33]; effect sizes were not clearly reported in the other [20]). One study found mixed results depending on the exact fear variable used, with significant
improvements in two of five analyses (aggregate effect size 2.7% [32]). The fourth study found a significant improvement in fear in a sample of young people
(9.8% [34]).

Ten further studies used uncontrolled designs to investigate similar interventions.
Most of these studies found some improvement, although significance was often not
reported. Seven studies showed a trend towards reduced fear (5.6% [21], 6% [25], 8% [23], 8% [24], 17% [30], 22% [28] and 35% [31]), and three studies showed no change or a trend towards increased fear (0% [36], −1% [22] and −6% [35]).

Finally, two studies investigated smaller-scale changes, both using uncontrolled designs.
One study investigated a change from conventional yellow sodium lighting to a new
bulb type with a whiter light in North West England [27], and the other study investigated an increase in brightness, carried out in Enkhuizen,
the Netherlands [37]. Both studies found significant reductions in fear of crime (19.7% [27] and 15.1% [37]).

Overall, the evidence regarding lighting is rather mixed. While the uncontrolled studies
showed reductions in fear, these were generally not replicated in more rigorous studies,
although some of the latter studies did show some positive effects.

3. Installation of closed-circuit television (CCTV) systems

Six studies investigating the effect of CCTV on fear of crime were identified, five
studies from the UK and one study from the USA. Three controlled studies were identified.
One of these studies was incompletely reported and did not appear to show any substantial
change in fear levels [39]. The second controlled study, carried out in New York City, NY, USA, investigated
the effect of the installation of CCTV in a public housing project with transmission
to residents’ television sets. It showed very mixed findings, with improvements in
some fear outcomes and adverse changes in others (median 9.8% [42]). The third and largest study concerned the effects of installations of CCTV in four
town centers and five residential areas in England. It found some within-group reductions
in fear (median within-group effect, 5%), but little evidence of reduced fear when
the control group was taken into account: out of sixteen analyses reported, only six
showed positive comparative trends in fear outcomes (of which two were statistically
significant) [40].

Three uncontrolled studies in England evaluated the impact of CCTV. Two studies showed
slight positive trends (2% [38] and 2.5% [43]), and one study showed a negative trend (−7.5% [44]). Statistical significance was not measured in any of these studies.

Overall, the evidence tends to show that CCTV is not effective in reducing fear of
crime, although the quality of the evidence is limited.

4. Multi-component interventions for crime prevention

Nine studies investigated large-scale programs of environmental change to address
crime or the fear of crime. Eight studies were based in various cities in the USA
and one study was based in London, UK. Intervention components often included security
improvements, lighting improvements and installation of CCTV, as well as more general
environmental improvements such as landscaping or graffiti removal. In addition, many
included non-built-environment components such as changes to policing practice (for
example community-oriented policing) and/or social programs (for example drug treatment,
employment initiatives). A range of settings were investigated, including residential
and business areas, parks, schools and public transport stations.

Three controlled studies reported trends towards reductions in fear of crime [45,51,61]. Two of these studies investigated broad environmental crime reduction programs in
residential areas in Chicago, IL, USA (6% [45]), and Hartford, CT, USA (4% [51]), which in one case was reported to reach significance, although the analysis is
non-standard [51]. The third study focused on public transport stations in London and showed a positive
trend in fear, although significance was not reported (7.5% [61]).

However, two further controlled studies showed small and non-significant adverse trends
towards increased fear: one study of a police-led intervention in Oakland, CA, USA,
to address environmental problems at crime ‘hot spots’ (change scores not reported
[59]), and the other study of a security program in schools in Broward County, FL, USA
(−3.8% [55]).

Two uncontrolled studies also showed reductions in fear of crime: one study of a police-led
intervention in a crime ‘hot spot’ in a park in Pennsylvania, PA, USA (29.8% [47])a, and the other study in a public transport setting in New York City (21% [50]), although significance was not reported. One further uncontrolled study of an intervention
focusing on road closures in Dayton, OH, USA, showed a non-significant trend toward
reduced fear (6% [48]). A fourth uncontrolled study showed mixed results, although with a median positive
trend (5% [56]).

Overall, the findings on multi-component environmental crime reduction programs are
mixed and do not constitute strong evidence of effectiveness in reducing fear.

5. Housing improvement and relocation

Seven studies, all carried out in UK cities, examined the effects of housing improvement
on fear of crime outcomes. Three studies included renovation of existing housing [63,66,69], one study focused on the provision of new housing and relocation of residents [70], and three studies included elements of both [62,65,67].

Three controlled studies all showed small and non-significant improvements in fear
of crime (2.5% in Liverpool [65] and 7% in London [62]; change scores are not reported for the third study, carried out in Hull and London
[66]). Four uncontrolled studies showed varying results, with two studies showing significant
reductions in fear of crime (9.1% [70]b and 16.1% [63]), one study showing no change (1.5% [69]), and one study showing significant adverse effects in fear (−19% [67]).

The findings on housing are very mixed. The variation in findings does not seem to
depend on whether studies involved substantial relocation or not (as might be hypothesized,
since relocation would disrupt social networks, thus potentially increasing fear of
crime). However, there are some positive findings from reasonably robust studies.

6. Area-based regeneration initiatives

There were two studies in this category, involving large-scale nationwide urban regeneration
programs conducted in the UK. Both the Single Regeneration Budget (SRB) [75] and the New Deal for Communities (NDC) [72] included a wide range of component initiatives (for example housing, environmental
improvement, employment and economic development initiatives, and crime prevention).
In both studies there was no clear trend in fear outcomes. The SRB evaluation showed
a 2% within-group improvement [75]. The NDC evaluation showed substantial improvements in the intervention group over
the timeframe of the evaluation (median within-group change, 13.5%), but similar improvements
were also found in the matched comparison group, so may not be attributable to the
intervention (median comparative change, −2.5%) [72].

7. Small-scale environmental improvements in public areas

One controlled study from the USA and one uncontrolled study from the UK looked at
small-scale environmental improvements which were not primarily aimed at reducing
crime. In the USA study, new gym equipment was installed in urban parks in Southern
California, and general environmental improvements were carried out [76]. The UK study was set in Durham in the North of England, and involved cleaning and
repainting a bus station [77]. Both studies found significant improvements in at least some fear of crime outcomes
(change scores not reported in one study [76]; a significant 8.1% improvement in perceived risk, but no significant change in feelings
of safety (change scores not reported) in the other study [77]).

Population subgroups and inequalities

Most information on the differential effect of interventions related to age and gender.
Ethnicity was investigated in one study alone [72] and the effects of socioeconomic status, or relevant proxy measures, on outcomes
were not investigated in any studies. Supplementary Additional file 3 discusses the findings and presents harvest plots for age, gender and ethnicity.

The findings on age were mixed, with some studies showing greater effect in older
people and some showing greater effect in younger people. The findings on gender tended
to show slightly greater improvements for women than for men. However, the only study
to directly measure an interaction between intervention exposure and gender was the
non-crime-focused intervention in Durham, which found consistently greater effectiveness
for men than women across four outcomes; however, only in one outcome did the difference
reach significance [77].

Discussion and conclusions

The findings of this review indicate that some environmental interventions may have
the potential to reduce fear of crime, although in no case is the evidence conclusive.
The most promising categories of intervention appear to be home security improvements
(category 1), at least in certain contexts, and general environmental improvements,
for which some limited evidence was found (category 7). In most other categories there
was little evidence of reducing fear of crime. Where positive findings emerged from
non-comparative studies, they were rarely confirmed by more robust designs with matched
comparison groups. In some cases, such as street lighting (category 2), effect sizes
found in controlled studies were lower than in uncontrolled studies.

Installation of CCTV (category 3) appeared to be the least promising of the interventions,
with consistent evidence of ineffectiveness in reducing fear of crime; however, it
is possible that these findings may be confounded if CCTV was installed in areas known
to be crime ‘hot spots’.

Findings in the other four categories were more equivocal, with some positive findings,
though none provide strong evidence of reductions in fear of crime. Of concern is
the finding from one study of increased fear of crime [67]. This was a large housing improvement program in Glasgow, Scotland; the study authors
speculate that relocation may have had disruptive effects on social networks, hence
increasing fear of crime. This hypothesis remains to be tested.

In general, the evidence base covered in the review has considerable limitations.
Study quality is generally poor, with very few studies using robust designs with adequately
matched control groups, and many studies not conducting appropriate statistical analyses.
For those categories containing few rigorously conducted studies, CCTV and multi-component
environmental programs in particular, the results should be regarded as indicative
only.

One of the most serious limitations of the evidence base is the heterogeneity in the
outcome measures aggregated as ‘fear of crime’ in this review. This heterogeneity,
and the associated problems with the concept of fear of crime itself, have been subject
to sustained critique. The different definitions of fear have been shown to lead to
widely varying empirical results and arguably do not access the same underlying construct
[78-81]. Supplementary Additional file 4 shows the different types of fear of crime outcome measures included in the studies;
as shown, there is wide variation in the types of outcome included. While we have
simply aggregated these distinct outcomes in this review as though they referred to
the same construct, it should be borne in mind that the heterogeneity of measures
places limitations on what can be inferred from the results. In particular, several
of the studies with the most positive trends only measured perceived safety, rather
than affective fear; [50,61,76,77] such outcomes could be hypothesized to have a lesser impact on wellbeing.

Positive mental health is increasingly recognized as an important aspect of public
health and may be influenced by good living environments, housing, employment, transport,
education and a supportive political structure; and at a community level, by a sense
of belonging, social support, a sense of citizenship and participation in society
[82]. Fear of crime is one important mechanism (or pathway) which mediates the relationship
between these influences and mental health and wellbeing. This review has found some
support for the role of physical environment as a target for effective interventions,
although further evaluative evidence is needed. As both crime and mental health and
wellbeing are strongly socially patterned, future research should also have a clearer
equity focus particularly taking account of socioeconomic status, ethnicity and gender.

Endnotes

a The Pennsylvania, PA, USA, study [47] was conceived as a controlled design, but is treated in this review as uncontrolled
because the comparison group appear to have benefited from the intervention as much
as the ‘intervention’ group.

b The Petticrew et al. study in Scotland [70] used a controlled design, but only within-group findings are available for fear outcomes.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

The idea for the study was formulated by MP and MW, with input from HT, SCu, AS and
AR. Searches were conducted by KW. Screening and coding were conducted by TL, DN and
SCl. TL conducted the data analysis and wrote the first draft of the manuscript. All
authors contributed to revising the manuscript and approved the final draft.

Acknowledgements

This project was funded by the National Institute for Health Research Public Health
Research (NIHR PHR) Programme (project number 09/3000/14). The views expressed are
those of the authors and do not necessarily reflect those of the NIHR. We would like
to thank the members of the project Advisory Group: Allan Brimicombe, John Middleton,
David Nossiter, James Thomas, Rachel Tuffin and Sandra Walklate.

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